Study of Seismic Base Isolation of Bridge Considering Soil Structure Interaction

In this paper, a comprehensive study of seismic response of base isolated bridge is made by varying different parameters such as soil stiffness, embedment depth, hydrodynamic pressure and earthquake response spectrum. The object is to determine effect of soil-structure interaction on seismic response when isolation by elastomeric bearing is provided between superstructure and substructure. Elastomeric bearing is seen to be effective in reducing seismic response of substructure on rocky site. The increase in embedment depth also causes reduction in bending moments and shear forces in the substructure. The use of elastomeric bearing in place of Rocker-Roller bearing is seen to be beneficial from seismic considerations

Seismic Behaviour of Bridges Considering Soil-Structure Interaction

The soil-structure interaction has significant effect on seismic response of bridges in many situations. The choice of soil springs for response determination is an important consideration. This paper presents a comparative assessment of the seismic response of bridge substructure by four different types of frequency independent soil springs namely, Beredugo-Novak, Wolf, Bycroft-Parmelee and Terzaghi. The variation of equivalent weighted damping and equivalent seismic coefficient is also studied. The Terzaghi\u27s soil springs obtained by modulus of subgrade reaction approach are most flexible as compared to others. The responses are seen to be comparable with springs other than Terzaghi. The equivalent damping in higher modes is increased due to energy dissipation in soil. The codal provisions of equivalent seismic coefficient variation below scour level are generally unconservative

Technique and Role of Embolization using Ethylene Vinyl-Alcohol Copolymer before Carotid Body Tumor Resection.

A 45-year old female referred for a large carotid body tumor resection. The tumor was encasing the internal (ICA) and external carotid arteries (ECA). She underwent angiogram and embolization of the ascending pharyngeal artery and a distal branch of the ECA using ethylene vinyl-alcohol copolymer (EVOH). Two days later, surgical resection of the tumor with regional lymph node dissection was performed along with an interposition reversed vein graft anastomosis between the mid common carotid and distal ICA. Devascularization of carotid body tumor can be performed using EVOH delivered through trans-arterial and percutaneous routes. Embolization may facilitate surgical resection and decrease blood loss but does not decrease the rate of neurological complications. Embolization can be performed by the vascular surgeon before a large carotid body tumor resection with minimal migration and or stroke risk

On the origin of the artesian groundwater and escaping gas at Narveri after the 2001 Bhuj earthquake

At Narveri, north of Khavada in the Great Rann of Kachchh, an outflow of groundwater continued even more than four months after the Bhuj earthquake of 26 January 2001, although at a considerably reduced rate compared to that immediately following the earthquake. Air or gas bubbling through the freshly oozing water has also been observed. We had collected a large number of samples from different parts of Gujarat, where post-earthquake groundwater outpourings were reported. Narveri, however, was the only site where the samples showed dissolved helium concentrations, significantly above the air equilibration value. Based on measurements of helium, radon, chloride, sulphate and sodium concentrations and temperature, we suggest that the flowing water and escaping gases at Narveri have a deep confined source with a reservoir age in excess of ~ 104 years

Medical research and ethics - Revisited

Ethics in the medical research is known since many years; however, there have been new developments in this area recently. A phenomenal improvement in the health-care system, leading to increased life expectancy, and thereby, newer lifestyle and other health-related diseases has opened avenues for newer drugs and health-care technology. However, these have to be tried and tested in the context of the disease epidemiology, health-care delivery and of course, medical ethics. Monitoring and evaluation of the treatment regimes of well documented effective medicines is also required. This is the core of medical research. With the ever increasing concept of evidence-based medical system, and thereby, a rapid rise in the number of clinical trials; the role of medical ethics is potentially increasing to keep the patient

The Effects of Genetic and Pharmacologic Loss of the Notch4 Protein on Angiogenesis

Angiogenesis is the process by which new blood vessels form, as cells undergoing hypoxia secrete Vascular Endothelial Growth Factor (VEGF), which prompts a tip cell phenotype in adjacent endothelial cells. The new tip cell expresses DLL4 and presents it on its surface, which binds to Notch receptors on neighboring cells and inhibits them from also becoming tip cells, forcing them to adopt the stalk cell phenotype. Notch signaling is critical to the tip/stalk cell fate decision, and both Notch1 and Notch4 are expressed in the vasculature, but not much is known about the different roles and parallel functions of Notch4 in contrast to the well-studied Notch1. In order to quantify the effects of removing Notch4, Notch4 mutants were generated via genetic mutations, or Notch4 function was inhibited by an anti-Notch4 neutralizing antibody. The vasculature of postnatal retina from control animals was compared to either knockout or anti-Notch4 treated mice on measures of radial outgrowth, tip cell count, vascular density, large vessels count, and branching. The experimental groups were then compared to each other to understand the degree to which pharmacologic inhibition recapitulates the genetic knockout phenotype. Our data shows that the Notch4 genetic knockout mice tend to exhibit decreased radial outgrowth and reduced branching. This supports the hypothesis that Notch1 and Notch4 have unique targets, as Notch1 knockouts show a stark increase in tip cell density, which is not seen in Notch4 genetic knockouts. In contrast, the pharmacologic Notch4 knockouts resembled the Notch4 genetic knockouts in radial outgrowth, but Notch1 mutants in tip cell density, though the reason why is not yet known. The mapping of angiogenic pathways is of consequence because it offers many avenues for studying human health. For example, new cancer research aims to reduce blood flow to tumors by decreasing angiogenesis, and published data suggests that knocking out Notch4 reduces tumor perfusion and growth. Therefore, a deeper understanding of the role of Notch4, and in turn, angiogenesis, could aid the development of new medicinal therapies for some of our most deadly diseases

Behavior of Buildings in August 21, 1988 Bihar-Nepal Earthquake

A moderate size earthquake rocked Bihar-Nepal border at 4.40 hrs. on August 21, 1988 causing wide spread devastation leading to loss of many lives and economic loss to the people of that region. The paper describes the study of damages occurred in masonry buildings, reinforced concrete buildings and liquefaction of the soil. The weakness of construction causes of damage and lessons learnt from the performance of structures are highlighted. The traditional and old structures without any earthquake resistance measures has suffered greater damage. The new reconstruction and strengthening measures must take into consideration the experience of failure of structures